Typical Weir for flood water harvesting and stream diversion
A weir (sometimes called an overflow dam), is a small dam created across a valley or river channel and often used to create an impoundment reservoir. The term weir is also sometimes used to describe the crest of an overflow spillway on a large dam. In most cases, weirs take the form of a barrier across the river that causes water to pool behind the structure (just like a dam), but allows water to flow over the top. Weirs are commonly used to alter the flow regime of the river, prevent flooding, measure discharge. They are normally constructed using concrete, stone masonry or gabions. Most weirs are used to create a pool of water abstraction purposes but they are also used for flow measurement . They are also used for drinking water supplies or to control flooding and to help render a river navigable
WATER HARVESTING AND STORAGE IN VALLEYS USING WEIRS